WASHINGTON (CNN) -- A German-owned cargo ship was hijacked by pirates in the Gulf of Aden in waters near Somalia that have become notorious for pirate attacks.

Pirates continue to attack shipping in the Gulf of Aden despite international naval patrols.

The Antigua and Barbuda-flagged ship, named Victoria, was seized Tuesday and 11 Romanian crew members were being held captive, said Lt. Nate Christensen, a U.S. Navy Spokesman.

Christensen said he did not know what cargo the ship was carrying.

Piracy has been soaring off the coast of eastern Africa -- particularly Somalia, which has not had an effective government since 1991.

Somali pirates have defied foreign navies patrolling the waters and have collected large ransoms from shipping companies. Ransoms started out in the tens of thousands of dollars and have since climbed into the millions.

Meanwhile, the head of a shipping company recently victimized by pirates off the Somali coast told lawmakers Tuesday that U.S. cargo crews should be allowed to arm themselves in response to the rising hijacking threat.

Philip Shapiro, head of Liberty Maritime Corp., told a U.S. Senate Commerce subcommittee that the owners of U.S.-flagged "have done all they can within the law to protect our crews."

Don't Miss

Unfortunately, he said, U.S. vessels are still largely at the mercy of pirates in shipping lanes around the heavily trafficked Gulf of Aden.

"In light of the recent threats to U.S. merchant mariners, we respectfully request that Congress consider clearing the obstacles that currently block ship owners from arming our vessels," Shapiro said.

Pirates unsuccessfully attempted to board the Liberty Sun, a cargo vessel owned by Shapiro's company, near the Somali coast on April 14. The ship was on a humanitarian relief mission at the time, carrying 47,000 tons of food to Mombassa, Kenya.

Pirate leaders later said the attempted hijacking was carried out as revenge after the U.S. Navy killed three pirates involved in a failed attack on the cargo ship Maersk Alabama. The slain pirates were holding Capt. Richard Phillips, who was in charge of the Alabama when it was boarded April 8.

"We've heard some suggestions that U.S.-flagged ship owners have not done enough to protect their vessels," Shapiro said. "That view ... is flat wrong. Our company adopted every measure recommended by the international maritime organizations and required by the Coast Guard's approved security plan for making the vessel a difficult piracy target -- and more."